La trazabilidad en las mediciones del laboratorio clínico: impacto en la calidad y seguridad del paciente / Traceability in clinical laboratory measurements: impact on quality and patient safety

Las mediciones confiables, trazables metrológicamente y comparables proporcionan la base racional para la evaluación de la calidad de un resultado y el fortalecimiento de las redes de laboratorios clínicos, lo cual permite mejorar la calidad de atención y la seguridad del paciente. En este documento se revisan los principios básicos que deben seguirse para garantizar la trazabilidad de las mediciones del laboratorio clínico, las ventajas de utilizar métodos trazables, el impacto de no hacerlo, y se discuten las principales limitaciones para relacionar las mediciones con los estándares de medición de referencia apropiados

Reliable, metrologically traceable, and comparable measurements provide the rationale for evaluating the quality of a result and strengthening clinical laboratory networks, thereby improving quality of care and patient safety. This document reviews the basic principles that must be followed to ensure the traceability of clinical laboratory results, the advantages of using traceable methods, the impact of not doing so, and the main limitations in relating measurements to appropriate reference standards

A rapid assessment of health system preparedness and response to the COVID-19 pandemic in Guinea

Epidemic-prone diseases have high adverse impacts and pose important threats to global health security. This study aimed to assess levels of health facility preparedness and response to the COVID-19 pandemic in Guinea. This was a cross-sectional study in public and private health facilities/services across 13 Guinean health districts. Managers and healthcare workers (HCWs) from departments in each facility/service were interviewed. Descriptive statistics and comparisons were presented using Pearson's Chi-Squared Test or Fischer exact test. Totally, 197 managers and 1020 HCWs participated in the study. Guidance documents and dedicated spaces for management/isolation of suspected COVID-19 cases were available only in 29% and 26% of facilities, respectively. Capacities to collect (9%) and safely transport (14%) samples were low. Intensive care units (5%), dedicated patient beds (3%), oxygenators (2%), and respirators (0.6%) were almost lacking. While 36% of facilities/services had received infection prevention and control supplies, only 20% had supplies sufficient for 30 days. Moreover, only 9% of HCWs had received formal training on COVID-19. The main sources of information for HCWs were the media (90%) and the internet (58%). Only 30% of HCWs had received personal protective equipment, more in the public sector (p<0.001) and in Conakry (p=0.022). This study showed low levels of preparedness of health facilities/services in Guinea and highlighted a lack of confidence among HCWs who felt unsafe at their workplace. Better governance to improve and maintain the capacity of the Guinean health system to respond to current and future epidemics is needed.

Tracing an Osmium Solution Standard to the International System of Units (SI).

The purpose of this work was to develop an accurate osmium (Os) solution standard that is traceable to the International System of Units, the SI. A gravimetric reduction (GR) method was developed to accurately assay the Os in ammonium hexachloroosmate salt, (NH4)2OsCl6, the chosen starting material for the Os solution standard. This GR method was also applied to -200 mesh high-purity Os metal powder, which served as an independent source of Os for comparison. An alkali fusion method was developed to create water-soluble salts from the Os metal GR products of both the (NH4)2OsCl6 and -200 mesh high-purity Os metal powder. Quantitatively prepared Os solutions from each of these water-soluble salts were compared by inductively coupled plasma spectrometry, ICP-OES. The purities of the Os starting materials were determined by quantitatively performed trace metallic impurities analysis, by ICP-OES and ICP-MS; the O, N, and H impurities were determined by inert gas fusion analysis. The percent purities of the starting materials were applied as corrections to the Os assay results obtained by GR. The agreement between these Os solutions, corrected for random and systematic errors by error budget analysis, confirmed the accuracy of the Os assay in the (NH4)2OsCl6. The SI traceability of the Os assay in the (NH4)2OsCl6 salt was established through the GR procedure and the purity analysis of this material. An SI traceable Os solution standard was gravimetrically prepared from this batch of (NH4)2OsCl6, based on the accurate Os assay and the percent purity of the starting material.

Redefinition of the Mole in the Revised International System of Units and the Ongoing Importance of Metrology for Accurate Chemical Measurements.

This Feature highlights the role of metrology, the science of measurement, in maintaining the infrastructure we all rely on for accurate chemical measurements. In particular, the recent change to the definition of the mole, the unit of chemistry, is explained.

[Redefinition of the International System of Units (SI) and Related Quantities in the Field of Ionizing Radiation].

The International System of Units (SI) is recommended for the practical system of units of measurement. The decision of redefining the seven base units of the SI (the second, the meter, the kilogram, the ampere, the kelvin, the mole and the candela) was made at the 26th meeting of the General Conference on Weights and Measures on 16 November 2018. This redefinition came into force starting 20 May 2019, and it became a big historic turning point for the metrology society. This is because the kilogram, the unit of mass, was defined only by an artifact as the international prototype of the kilogram, has been kept for 130 years since its determination in 1889, and was finally changed to the new definition by taking the fixed numerical value of the Planck constant on that day.It is easily imagined that the redefinition of the SI base units has a strong impact on our daily life or the field of science. The reason why the SI redefinition had to be adapted is introduced firstly. Then, how the new definitions are applied now after a year from the redefinition and future prospective of the new definitions are discussed. In the last, the impacts of the SI redefinition in the field of the ionizing radiation, especially in the fields of the medical application of the ionizing radiation, are discussed.

Cuantificación y descripción del ejercicio físico / Quantification and Description of Physical Exercise

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Insulin Units and Conversion Factors: A Story of Truth, Boots, and Faster Half-Truths.

Conventional insulin concentration units (IU/mL or just U/mL) are bioefficacy based, whereas the Système International (SI) units (pmol/L) are mass based. In converting between these two different approaches, there are at least 2 well-accepted conversion factors, where there should be only 1. The correct value is not the most-used or well-accepted using online calculators, some journal styles, laboratory reports, and published articles. In short, an incorrect insulin conversion factor is widely used which underreports insulin concentrations by ~15%, with potentially significant research and clinical implications. This short commentary describes the history of insulin IU definitions and conversion factors, and highlights the widespread nature of conversion factor misuse, to provoke deeper interest and thought regarding numbers we so often use without thinking.

Plasminogen activator system homeostasis and its dysregulation by ethanol in astrocyte cultures and the developing brain.

In utero alcohol exposure can cause fetal alcohol spectrum disorders (FASD), characterized by structural brain abnormalities and long-lasting behavioral and cognitive dysfunction. Neuronal plasticity is affected by in utero alcohol exposure and can be modulated by extracellular proteolysis. Plasmin is a major extracellular serine-protease whose activation is tightly regulated by the plasminogen activator (PA) system. In the present study we explored the effect of ethanol on the expression of the main components of the brain PA system in sex-specific cortical astrocyte primary cultures in vitro and in the cortex and hippocampus of post-natal day (PD) 9 male and female rats. We find that ethanol alters the PA system in astrocytes and in the developing brain. In particular, the expression of tissue-type PA (tPA), encoded by the gene Plat, is consistently upregulated by ethanol in astrocytes in vitro and in the cortex and hippocampus in vivo. Astrocytes exhibit endogenous plasmin activity that is increased by ethanol and recombinant tPA and inhibited by tPA silencing. We also find that tPA is expressed by astrocytes of the developing cortex and hippocampus in vivo. All components of the PA system investigated, with the exception of Neuroserpin/Serpini1, are expressed at higher levels in astrocyte cultures than in the developing brain, suggesting that astrocytes are major producers of these proteins in the brain. In conclusion, astrocyte PA system may play a major role in the modulation of neuronal plasticity; ethanol-induced upregulation of tPA levels and plasmin activity may be responsible for altered neuronal plasticity in FASD.

Nomenclatura y unidades de las propiedades biológicas. Recomendación (2016) / Nomenclature and units of biological properties. Recommendation (2016)

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Fully international system of units-traceable glycated hemoglobin quantification using two stages of isotope-dilution high-performance liquid chromatography-tandem mass spectrometry.

Glycated hemoglobin (HbA1c), defined as hemoglobin (Hb) molecules having a stable adduct of glucose on the N-terminal of the ß-chains, has been endorsed as a diagnostic tool for diabetes mellitus and a prediction indicator for the development of diabetes complications. Here we describe an accurate procedure using two stages of isotope dilution-ultra performance liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) for the quantification of HbA1c that provides full traceability to International System of Units (SI). First, synthetic peptides representing specific markers of HbA1c (G-hexa) and hemoglobin A0 (Hexa) were certified by amino acid analysis via acid hydrolysis as reference materials (RMs) for the next step. For this peptide certification, three amino acids (proline, valine, and leucine) were determined by hydrolysis with 10M hydrochloric acid at 130°C for 48h followed by ID-LC-MS/MS. Then, HbA1c content in blood was quantified with the ratio of specific proteolytic peptides from HbA1c and HbA0 via enzyme digestion using ID-LC-MS/MS with the certified peptides as RMs and isotope-labeled peptides as internal standards. Results demonstrate complete traceability to SI-units throughout this procedure. Reliability was confirmed through comparative studies with commercially available RMs for HbA1c, and other routine HbA1c diagnostic methods as well. Following full method validation, we applied this procedure to the certification of candidate hemolysate-certified RMs for HbA1c content, as well as 52 real clinical samples. All of the results showed the suitability of this method to act as a primary reference measurement procedure for HbA1c in complex biological samples.

Certified Reference Material for Use in 1H, 31P, and 19F Quantitative NMR, Ensuring Traceability to the International System of Units.

In recent years, quantitative NMR (qNMR) spectroscopy has become one of the most important tools for content determination of organic substances and quantitative evaluation of impurities. Using Certified Reference Materials (CRMs) as internal or external standards, the extensively used qNMR method can be applied for purity determination, including unbroken traceability to the International System of Units (SI). The implementation of qNMR toward new application fields, e.g., metabolomics, environmental analysis, and physiological pathway studies, brings along more complex molecules and systems, thus making use of 1H qNMR challenging. A smart workaround is possible by the use of other NMR active nuclei, namely 31P and 19F. This article presents the development of three classes of qNMR CRMs based on different NMR active nuclei (1H, 31P, and 19F), and the corresponding approaches to establish traceability to the SI through primary CRMs from the National Institute of Standards and Technology and the National Metrology Institute of Japan. These TraceCERT® qNMR CRMs are produced under ISO/IEC 17025 and ISO Guide 34 using high-performance qNMR.

The ratio of glycated albumin to hemoglobin A1c measured in IFCC units accurately represents the glycation gap.

The glycation gap (G-gap: difference between measured hemoglobin A1c [A1C] and the value predicted by its regression on the fructosamine level) is stable and associated with diabetic complications. Measuring A1C level in International Federation of Clinical Chemistry (IFCC) units (A1C-SI; mmol/mol) and National Glycohemoglobin Standardization Program units (A1C-NGSP; %) and using glycated albumin (GA) level instead of fructosamine level for calculating the G-gap, we investigated whether the G-gap is better represented by GA/A1C ratio if expressed in SI units (GA/A1C-SI ratio) rather than in NGSP units (GA/A1C-% ratio). We examined 749 Japanese children with type 1 diabetes using simultaneous GA and A1C measurements. Of these, 369 patients were examined more than five times to assess the consistency of the G-gap and the GA/A1C ratio within individuals. The relationship of GA/A1C-% ratio to the corresponding A1C-NGSP was stronger than that of GA/A1C-SI ratio to A1C-IFCC. At enrollment, the inverse relationship between the GA/A1C-SI ratio and G-gap was highly significant (R(2) = 0.95) compared with that between the GA/A1C-% ratio and G-gap (R(2) = 0.69). A highly significant inverse relationship was also observed between the mean GA/A1C-SI ratio and the mean G-gaps obtained individually over time (R(2) = 0.95) compared with that using the corresponding A1C-NGSP (R(2) = 0.67). We conclude that the G-gap is better represented by the GA/A1C-SI ratio. We propose the use of mean GA/A1C-SI ratios easily obtained individually over time as reference values in Japanese children with type 1 diabetes (6.75 ± 0.60 [means ± SD]).

International reference preparations for standardization of biological medicinal products.

International standards are prepared as materials assigned an arbitrary unitage for a biological activity by the Expert Committee on Biological Standardization of the World Health Organization. Working reference materials are calibrated against international standards giving a common unit of measurement between laboratories. The references are assessed by a collaborative study including all relevant assays rather than by a single reference method as in the SI (Le Système international d'unités) system and the unitage assigned is an arbitrary value derived from a consensus of all valid methods. The process has proved valuable in assaying the activity of therapeutic biological medicines and in standardizing certain types of diagnostics. Issues arise with maintaining the unit when the primary reference must be replaced and to some extent in assessing the commutability of the reference with real life analytes.